Magnetic structure



Jan. 3, 1933. H. E. KENNEDY MAGNETIC STRUCTURE Filed July 3, 1931 ri s/a w n/i INVENTOR. MRRY f. KENNEDK 1: W. A TTORNEYS.

Patented Jan. 3, 1933 A HARRY E. KENNEDY, F BERKELEY, CALIFORNIA MAGNETIC STRUCTURE Application filed Ju1y 3,

when the plunger is just entering, a relative-' ly feeble force exists which rapidly increases.

as'the plunger continues to enter until a maximum is reached after which no change takes place until a point is reached when the force tends to diminish to zero and thereafter reof these two forms are satisfactory for certain functions such as in operating a reciprocable fuel metering valve and like devices where a relatively large initial force is necessary to overcomeinertia, spring pressure and the force resulting from an. unbalanced oil pressure. The main reasons forthis is that it is desirable in such devices that the electromagnet utilized in operating reciprocable parts thereof be capable of exerting its maximum force at the beginning of the stroke.

It is the principal object of the present invention to provide an improved magnetic structure particularly applicable for operating such devices as reciprocable valves where in it is essential that the elect-romagnet be capable of exerting its maximum force at the beginning of its operation.

M This object is accomplished by constructing the stator with a pole face made up of stratified sections of varying magnetic reluctance across its active face and may be constructed of alternate strata of magnetic and non-magnetic material. A winding is provided so that alternate poles are formed around thecircumference of the armature of the magnetic structure when energized. The armature which carries the reciprocable element is also provided with an outer strati-' fied face, said face having magnetic characterverses its direction. I have found that neither 1931. Serial No. 548,834.

istics similar to the stator, said armature may be constructed of magnetic material alternating with non-magnetic materiah It will be clear that when the armature is placed within the stationary portion of the magnetic structure in such a position that the magnetic laminae are in registry with one another, the reluctance of the magnetic circuit will be a minimum and this will be the position which the armature will assume when the winding is energized and there is no restraint on the armature. If, however, the armature be displaced in either direction by less than the thickness of the strata a restoring force will result tending to re-establish equilibrium. The force of attraction of an electromagnet for its keeper varies as the square of the number of lines of induction and directly as the area at the coacting surfaces. If we displace this armature, the flux density will increase until a point is reached where the increased reluctance of the magnetic circuit due to the diminution in area begins to diminish the total pull at which point the maximum restoring force will exist. In order to diminish the counter attraction of the adjacent strata the non-magnetic strata is preferably thicker than the magnetic strata. The total travel of the armature is determined by the thickness of the magnetic strata less the overlap' as determined by adjustment. The armature acquires kinetic energy as it accelerates toward the equilibrium position, and so is capable of overshooting this position. In so do- 5 ing it encounters a counter-magnetic force tending to retard it. In over-traveling this position of equilibrium the kinetic energy acquired'by the armature is reconverted into electrical energy instead of appearing as heat at the impacting surface of a stop.

However. under certain conditions a stop mav lie-used beneficially.

If laniinations are utilized in constructing this electromagnetic structure for use where a fluid pressure is to beretained by said laminations. the laminations may be sealed by the insertion of fibrous material between the lamin'ations, for example. as paper. or a soft coating of copper or lead plating, or gaskets may be used if necessary.

- is exemplified in the following description and illustrated byway of example in the accompanying drawing, in which:

Fig. 1 is a side view, partly in section, of an electromagnetically actuated valve illustrating the invention.

Fig. 2 is a plan view, partly in section, taken through section II II in Fig. 1.

Fig. 3 is a plan view, partly in section taken through section III-III of Fig. 1.

Fig. 4 is an erlarged sectional side view of a fuel nozzle and its associated parts which may be employed with the invention.

Fig. 5 is an enlarged sectional View taken through section VV of Fig. 3.

Fig. 6 is a similar view with the armature moved to its raised position.

Fig. 7 is a similar view of an alternative construction which may be employed utilizing all magnetic laminations and a stepped pole face;

Fig. 8 is a similar view of another construction utilizing multiple laminations per magnetic pole strata.

Fig. 9 is a similar view of a still further construction utilizing a non-laminated magnet structure with a stepped pole face.

Fig. 10 diagrammatically illustrates a wiring diagram which may be employed in this invention. I

Referring to the accompanying drawing in Fig. 1, I have illustrated an electro-magnetically actuated fuel injection valve as one form which my invention may assume, in which a lower base 11 carries a valve nozzle 12, suitably attached thereto. However in some instances it may be advantageous to retain the nozzle in a fixed position by clamping it with a suitable retainer in anv well known manner in order that the orifices 13 may assume any predetermined position relative to base 11. A removable hardened valve seat 10 may be employed for the benefit of alignment or to utilize a different material. This seat 10 is held in place by a valve guide 9 which preferably forms a very close running fit on the valve stem 15 to assure positive alignment with the valve seat. A collar or shim 8 extending between the nozzle and the base 11 may be replaced by others of varying thicknesses in order to accomplish an adjustment and thereby determine the lowermost position the armature will assume. A spring 45 acts against the end 46 of the valve stem 15, and is operatively associated with the spring adjusting rod 47, which is provided with a handle 48 for manual adjustment, and is sealed from leakage by the stufling box assembly 49. From the foregoing it will be obvious that the normal position of the armature is determined by the adjusting washer 8 which is preferably so adjusted as to place the armature in a position of maximum pull relative to the stator as illustrated in Fig. 5.

A valve 15 is rigidly attached to a laminated armature 16 which is retained in place by the nut 17 thereon. An electroma etic structure 21 is preferably composed o laminations such as 22 and 23 of alternately magnetic and non-magnetic material, and displaced in axial alignment with the magnetic laminations v19 of said armature. The nonmagnetic laminations 19 should be preferably of some material of low specific gravity such as aluminum in order to reduce inertia.

A winding 25 is disposed through holes 26 in the laminations and wound so that it forms four alternate poles around the circumference of the armature when energized. This winding is similar to a multipolar field windin of a single phase induction motor. A slot 2 is provided between the hole 26 and the armature 16 in order that the magnetic flux will not have an iron path across the inner edge of the hole 26.

A ring 31 is insulated from the laminations by an insulating washer 32 at its lower side, a washer 33 at the upper side and bushings 34 between said ring and the thru studs 38. One end 29, of the winding 25, is firmly attached to the insulated ring 31 which carries a suitable binding post 35 thereon for attaching the actuating current supply. The other end of the coil is firmly grounded to the frame. The upper body 41, carries a spring housing 42, rigidly attached thereto, through which the fluid may be introduced as by the connection 43 and the fluid supply line 44. The studs 38 by means of the nuts 39, retain the upperbody 41 in a fixed relation to the valve base 11, and firmly clamp the intermediate laminations, insulations and rings so as to prevent the leakage of the fluid from the interior thereof when under pressure.

The spring pressure may be adjusted by means of turning handle 48 through the medium of the screw threads to thereby equal-- ize the operation of the various valves on a multicylinder motor, after having adjusted the valve seats to retain the armatures in substantially the same lower positions.

In Fig. 5 I have illustrated the approximate relative positions of the armature lamination 16 relative to the magnet laminations 21 in which the magnetic layers 18 and 23 are latplrally displaced for maximum magnetic pu In Fig. 6 I have illustrated the laminations in axial alignment which would correspond to the position they would assume providing there was no exterior force acting on the armature to displace it when the magnet was energized.

In Fig. 7 I have illustrated an alternative type of construction which may be incorporated in the armature and/or magnet in which they are composed of all magnetic laminations, but with the alternate laminations stepped back from the pole face. (A pole face as herein employed throughout this application means a face similar to section AA of the various views.) Inthis construction it is preferable to employ a thicker stepper back lamination 51 relative to the pole lamination 50.to prevent an excessive fiux leakage from the lower lamination 52 to the armature lamination 53 whenin the lowermost position.

In'Fig. 8 I have illustrated asimilar construction whereby each efiective magnetic strata may be composed of multiple laminations of magnetic material wherein laminations 55, 56 and 57 constitute the magnetic pole face strata, the intermediate strata being composed of either the stepped back or nonmagnetic construction.

In Fig. 9 I have illustrated a construction wherein the magnet and/0r armature may be composed of a non-laminated material constructedwitha stepped pole face preferably 7 consisting of wider gaps than the'magnetic I stood thatsaid pole strata.

In Fig. 10-I have illustrated a diagram of the wiring which may ing the magnetic structure to alternately 0ppositely polarize the electromagnet about its armature. VVhile' this is shown as a single phase winding, it is obvious that a multiple phase winding may be employed and that the winding may be incorporated with either the magnet or the armature as production and construction may best decree. A current from any suitable operating circuit may be supplied to said winding to accomplish the results required. It is further to be underpoles, but may consist o any even number of po es.

. It is obvious that I have provided a magnetically actuated structure wherein the pull is greatest at the initial point-of movement and wherein the air gap remains substantially constant during operation and may be reduced to the minimum. In fact, I recommend a very close running fit between the armature and the magnet and by utilizing 1 the non-magnetic laminations on at least one of these units,'a smooth surface will be provided to prevent the necessity of additional bearings.

While 1 have illustrated and described this invention as actuating a fluid metering valve be employed in wind-' winding is not limited to four 1. In an electromagnetic structure, a sta tor, an armature asso. iated therew th and movable in an axial path, the coacting pole faces of the armature and stator being formed with complemental magnetc and non-magnetic regions alternately arranged axially of the path of movement of the armature to create alternate areas of high and low flux density.

. 2. In an electromagnetic structure, a stator, an armature associated therewith and movable in an axial path, the coact'ng pole faces of the armature and stator being formedof complement-a1 stratifications of magnetic and non-magnetic material, the stratifications be in g d. sposed transversely to the path of movement of the armature to create alternate areas of high and low flux density.

3. In an electromagnetic structure, a stator, an armature associated therewith and movable in an axial path, the coacting pole faces of the armature and stator being formed with complemental areas of magnetc and nonmagnetic metallic surfaces arrange-d alternately and axially of the path of movement of the armature to create alternate areas of high and low flux density. I

4. In an electromagnetic structure, a stator, an armature associated therewith and movable in' an axial direct'on', the coa-cting pole faces of the armature and stator being formed of spaoedareas of magnetic material. said areas being spaced axially of the path of movement of the armature to create alternate areas of high and low flux density, the armature when not energzed being positioned with its magnetic areas out of exact register with the magnetic areas of the stator and when energized said areas tending to come into substantial register.

In an electromagnet c structure, a stator including spaced magnetic laminations, .an armature associated with the stator and composed of spaced magnetic laminations complemental to the laminat ons of the stator. the single laminations of the stator being oppositely polarized about the armature, the

laminations of the armature and stator forming spaced magnetic paths of h gh flux densian armature assoc ated with the stator for movement in a path at right angles to the plane of the laminations, said armature being formed with alternate lamina-tions of magnetic and non-magnetic material complemental to the laminations of the stator, the armature when not energized being arranged with its magnetic laminations out of exact register with the magnetic laminations of the stator and when energized the said magnetic laminations tending to come into substantial register and thereby impart movement to the armature.

7. An electromagnetic structure including a stator and an armature mov'able in an axial path, the pole face of the stator and armature creating a multiplicity of magnetic paths between said armature and said stator, said paths being Stratified and in planes at right angles to the path of movement of the armature and being of alternately high and low reluctance.

8. In an electromagnetic structure, a stator includinga series of laminations having a chamber formed therein for the reception of an armature, an armature arranged in said chamber for coaxial movement therein, the pole faces of said armature and laminations being formed to create a series of magnetic paths transversely of the path of movement of the armature and of different reluctance.

9. In an electromagnetic structure, a stator having an opening formed thercthrough,'an armature arranged in said opening for axial movement therein, the coact ng pole faces of said stator and armature being such as to create stratified magnetic paths of different reluctance at right angles tothe path of movement of the armature.

' 10. in an electromagnetic structure, a stator, an armature associated therewith and movable in an axial path, the coacting pole faces of the armature and stator being formed with complemental magnetic and non-magnetic regions alternately arranged axially of the path of movement of the armature to create alternate areasof high and low flux density. means determining the relative postions of the magnetic regions of the armature and stator when the former is de-energized.

11. In an electromagnetic structure, a stator, an armature associated therewith and movable in an axial path, the coacting pole faces of the armature and stator being formed with complemental magnetic and non-magnetic regions alternately arranged axially of the path of movement of the armature to create alternate areas of high and low flux density, means determining the relative positions of the magnetic regions of the armature and stator when the former is de-energized, and other means limiting the movement of the armature from de-energized position.

12. In an electromagnetic structure, a

stator including alternately arranged magnetic and non-magnetic laminations secured together, an armature associated with the stator for movement in a path at right angles to the plane of the laminations, said armature being formed with alternate laminations of magnetic and non-magnetic material complemental to' the lamination of the stator, the armature-'when not energized being arranged with its magnetic laminations out of exact register with the magnetic laminations, of the stator and when energized the said magnetic laminations tending to come into substantial register and thereby impart movement to the armature, and means determining the relative position of the magnetic laminations of the armature and stator when the former is de-energized.

13. In an electromagnetic structure, a stator, an armature associated therewith and movable in an axial path, the coacting pole faces of the armature and stator being formed with complemental magnetic and non-magnetic regions alternately arranged axially of the path of movement of the armature to create alternate areas of high and low flux density, and yielding means constantly urging said armature to de-energized position with the magnetic regions of the armature and stator in a definite relative position.

14. In an electromagnetic structure, a stator, an armature associated therewith and movable in an axial path, the coacting pole faces of the armature and stator being formed with complemental stratifications of magnetic and non-magnetic material, the stratifications being disposed transversely to the path of movement of the armature and the thickness of the non-magnetic strata being greater than that of the magnetic strata, said stratifications creating alternate areas of high and low flux density.

15. In an electromagnetic structure, a stator, an armature associated therewith and movable in an axial path, the coacting pole faces of the armature and stator being formed with complemental magnetic and non-magnetic regions alternately arranged axially of the path of movement of the armature to create alternate areas of high and low flux density, the axial dimension of the nonmagnetic regions being greater than the similar dimension of the magnetic regions.

16. As an article of manufacture, a stator for an electromagnetic structure, said stator including a plurality of laminations of geometrical configuration secured together to form a unitary fluid-tight structure, said laminations being formed with complemental openings to form a chamber extending centrally through the structure for the reception of an armature, said structure being formed with recesses disposed intermediate the central opening and the peripheral surface of the structure for the reception of a winding, the said laminations being imperforate between said recesses receiving the winding and the peripheral surface of the structure, and imperforate caps forming-a part of the said stru'ctureand disposed at the opposite ends thereof to enclose the winding and an armature disposed in said central opemng.

17. An electromagnet, an associated armature, said eleotromagnet being laminated, a

fluid'conducting path extending through said laminations, said pathexposing' a portion of said laminations to said fluid pressure, other portions of said laminations being exposed to atmospheric pressure.

18. An electromagnetincluding laminations, a winding for said electromagnet, an armature associated with said electromagnet, a housing for one end of said electromagnet including a valve seat, a housing for the opposite endof said electromagnet, aninlet passage to one of said housings, said hous ings andsaid laminations forming a fluidtight conductor for fluid from said opening to'saidvalve seat. g

- 19. An electromagnet, a winding for said electromagnet, a fluld-tight inclosure inclosing said winding, said inclosure including a cover for said electromagnet, an insulated member adapted to be clamped to said cover,

said insulated member being connected with one end of said winding, said cover being capable of complete removal from said insu-' lated member whilesaid insulated member is connected to said windin a'portion of said insulated member extending outside of said fluid-tight inclosure.

- HARRY E. KENNEDY. 

